The specimens include a nearly complete Tarbosaurus bataar tyrannosaur, two hadrosaurs and this “oviraptors’ graveyard”, containing at least five skeletons.

Undercover agents identified the fossils in the possession of commercial palaeontologist Eric Prokopi, who last month was sentenced to three months in jail for illegally smuggling dozens of dinosaur remains. Among the haul was a tyrannosaur that was auctioned in New York for over &dollar;1 million – although the sale didn’t go through after the Mongolian government intervened. Personal ownership or export of dinosaur remains has been illegal in Mongolia since 1924.

Advertisement

“This is a historic event for the US Attorneys’ office, in addition to being a prehistoric event,” joked Preet Bharara, US attorney for southern New York, who handed over the fossils to Od Och, Mongolia’s UN ambassador, in a ceremony on 10 July.

Mongolia is welcoming its lost legacy with a new home. The capital city, Ulan Bator, has just one museum building, which until 1990 was an homage to Lenin. It will now become the nation’s first dinosaur museum.